Chen gave up two hits, walked a batter and struck out two. He threw 52 pitches, 29 for strikes.
The run scored on a Colby Rasmus double.
In two spring starts, Chen has allowed one run and three hits in five innings, with with one walk and five strikeouts.
I'm not including his intrasquad outing, when he failed to retire a third batter and had to be replaced.
Ryan Flaherty committed his second error at shortstop this spring.
Also, manager Buck Showalter told reporters that Tsuyoshi Wada will throw a simulated game on Wednesday and pitch in a real game on Sunday or Monday unless there's another issue with his elbow. Right now, he's doing fine.
Catcher Taylor Teagarden had an MRI on his back. X-rays haven't revealed any damage, but MRIs tend to give you the real story.
Hester would have the obvious edge at the moment, since he's been in camp a heck of a lot longer than Paulino.
Update: Galarraga gave up three runs in the fourth inning, and the Orioles lost to the Blue Jays, 4-1, in Dunedin.
The Orioles were held to three hits for the second straight game. Flaherty went 1-for-3 with an RBI. Steve Tolleson committed his second error.
Chen told reporters that he focused more on his two-seam fastball an offspeed pitches. He didn't throw enough strikes today.
"I feel bad that I was always behind in the count, but I still feel good today," he said through his interpreter.
"I didn't do a lot of adjustments today, but it was just a little hot for me today. The most important thing for me today was that I lost my tempo in the first two innings and in the third one I felt really, really good because everything was comfortable."
That comment about the heat will bring back some not-so-fond memories of Koji Uehara wilting in the early innings as a starter. Let's hope that Chen, who's projected to be in the rotation, proves to be more durable.